In recent years, attention is paid to a technology for embedding a digital watermark that adds various kinds of information to a digital content such as moving image data. For example, by embedding watermark information including copyright information, purchase information or the like relating to moving image data into the moving image data, when the moving image data leaks illegally through the Internet or the like, it is possible to specify the leaking source.
Further, a digital watermark may be utilized for presentation of detailed information regarding a commodity or a service to be introduced by moving image data that is utilized, for example, in a digital signage (electronic advertisement) or the like, distribution of coupons and so forth.
When watermark information is embedded into a digital content, it is desired to suppress deterioration of the content caused by embedding of the watermark information. As one of methods for suppressing deterioration of a content by embedding of watermark information, there is a method of determining a filter coefficient corresponding to embedding information to be embedded into an original signal and adjusting the phase of the original signal in accordance with the filter coefficient (refer, for example, to Japanese Laid-open Patent Publication No. 2004-341066). As a suppression method of the type described, there is a method of using the original signal after the phase adjustment as an embedding object signal.
When watermark information is embedded into a digital content, it is desired to suppress deterioration of the content caused by embedding of the watermark information. As one of technologies for suppressing deterioration of a content, there is a technology to determine a filter coefficient corresponding to information to be embedded into an original signal, adjust the phase of the original signal in accordance with the filter coefficient, and use the original signal after the phase adjustment as an embedding object signal (refer, for example, to Japanese Laid-open Patent Publication No. 2004-341066).
Further, when watermark information is embedded into a digital content, it is desired that information is not lost even if the content of image data or the like in which the information is embedded is processed. As one of technologies for suppressing loss of information embedded in a content, there is a technology to use, when a value of image data is changed while an edge and an isolated point in the image are preserved, a value between a value of an original picture and a value of an image after the image process as a change value (refer, for example, to Japanese Laid-open Patent Publication No. 2001-61055). Further, as another technology for suppressing loss of information embedded in a content, there is a method in which data in which a digital watermark pattern is embedded is analyzed to decide a degree of embedding of the digital watermark and an embedding parameter is adjusted based on the decision (refer, for example, to Japanese Laid-open Patent Publication No. 2010-258585). According to the technologies, it is possible to achieve both suppression of deterioration of a content and suppression of loss of information embedded in the content.